olympic combat sport injuries
TRANSCRIPT
OLYMPIC COMBAT SPORT INJURIES
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Injury incidence, severity, and profile in Olympic combat sports: a comparative
analysis of 7,712 athlete exposures from three consecutive Olympic Games
Reidar P. Lystad1,*, Alexander Alevras1, Iris Rudy1, Torbjørn Soligard2, Lars Engebretsen2,3,4
1 Australian Institute of Health Innovation, Macquarie University, Sydney, Australia
2 Medical & Scientific Department, International Olympic Committee, Lausanne, Switzerland
3 Oslo Sports Trauma Research Center, Oslo, Norway
4 Department of Orthopaedic Surgery, Faculty of Medicine, University of Oslo, Oslo,
Norway
* Corresponding author
Reidar P. Lystad
Australian Institute of Health Innovation
Faculty of Medicine, Health and Human Sciences
75 Talavera Rd
Macquarie University NSW 2109
Australia
T: +61 2 9850 2464
ORCID: 0000-0003-0506-0902
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ABSTRACT
Objectives To describe and compare the epidemiology of competition injuries in unarmed
combat sports (i.e., boxing, judo, taekwondo, and wrestling) in three consecutive Olympic
Games.
Methods Prospective cohort study using injury data from the International Olympic
Committee injury surveillance system and exposure data from official tournament records at
three consecutive Olympic Games (i.e., Beijing 2008, London 2012, and Rio de Janeiro
2016). Competition injury incidence rates per 1,000 minutes of exposure (IIRME) were
calculated with 95% confidence intervals using standard formulae for Poisson rates.
Results The overall IIRME was 7.8 (95%CI 7.0, 8.7). The IIRME in judo (9.6 [95%CI 7.8,
11.7]), boxing (9.2 [95%CI 7.6, 10.9]), and taekwondo (7.7 [95%CI 5.6, 10.5]) were
significantly higher than in wrestling (4.8 [95%CI 3.6, 6.2]). The proportion of injuries
resulting in >7 days absence from competition or training was higher in wrestling (39.6%),
judo (35.9%), and taekwondo (32.5%) than in boxing (21.0%). There was no difference in
injury risk by sex, weight category, or tournament round, but athletes that lost had
significantly higher IIRME compared to their winning opponents (rate ratio 3.59 [95%CI 2.68,
4.79]).
Conclusion Olympic combat sport athletes sustained, on average, one injury every 2.1 hours
of competition. The risk of injury was significantly higher in boxing, judo, and taekwondo
than in wrestling. About 30% of injuries sustained during competition resulted in >7 days
absence from competition or training. There is a need for identifying modifiable risk factors
for injury in Olympic combat sports, which in turn can be targeted by injury prevention
initiatives to reduce the burden of injury among combat sport athletes.
Keywords Athletic Injuries; Incidence; Combat Sport; Boxing; Judo; Taekwondo; Wrestling
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What is already known?
Combat sports have long-standing traditions in the Olympic Games.
Current data suggest that the risk of injury in combat sports is high, although there is
considerable variability in injury incidence rate estimates.
What are the new findings?
Olympic combat sport athletes sustain, on average, one injury every 2.1 hours of
competition.
The risk of injury is significantly higher in boxing, judo, and taekwondo than in
wrestling.
About 30% of injuries sustained during competition result in >7 days absence from
participation, with higher proportions in wrestling, judo, and taekwondo than in
boxing.
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INTRODUCTION
Combat sports have long-standing traditions at both ancient and modern Olympic Games.
Wrestling has been contested at every modern Olympic Games since the inception in 1896,
except for the Paris 1900 Olympic Games.[1,2] Similarly, boxing has been contested at every
modern Olympic Games since its introduction in 1904, except for the Stockholm 1912
Olympic Games.[3] More recent additions are judo, which was first introduced in 1964 and
has been contested at every Olympic Games since the Munich 1972 Olympic Games,[4] and
taekwondo, which has been contested since the Sydney 2000 Olympic Games.[5] Lastly,
karate will make its full Olympic debut at the Tokyo 2020 Olympic Games.[6]
Despite the popularity of Olympic combat sports worldwide, participation is not without risk
and injury is a common adverse outcome.[7] Previous systematic reviews of injuries in
Olympic combat sports have highlighted considerable variability in injury incidence rates
across primary studies.[7-10] This variability has been attributed to methodological
heterogeneity, including differences in operational injury definitions, exposure measures,
surveillance methods, study populations, and other contextual factors (e.g., changes in
competition rules over time). Unfortunately, this methodological heterogeneity has precluded
meaningful comparisons of injury risks and profiles across combat sports.
To remedy this, it would be ideal to implement identical and ongoing injury surveillance
systems across all combat sports; however, that would require access to considerable
resources and substantial cooperation and coordination between combat sport governing
bodies. An alternative and more realistic approach would be to leverage existing injury
surveillance systems at multisport events. For instance, injury data from the International
Olympic Committee (IOC) injury surveillance system,[11] can be combined with good
quality exposure data from official tournament records to enable direct and meaningful
comparisons of injury risks and profiles across Olympic combat sports, which in turn may
inform decisions about participation and the need for protecting the health and safety of
combat sport athletes.
The aim of this study was to describe and compare the epidemiology of competition injuries
in boxing, judo, taekwondo, and wrestling using data from the IOC injury surveillance system
and official tournament records at three consecutive Olympic Games (i.e., Beijing 2008,
London 2012, and Rio de Janeiro 2016). Specifically, the objectives were: (1) to quantify and
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compare competition injury incidence rates based on actual exposure time; (2) to quantify
and describe the distribution of competition injuries by body location, type of injury, and
injury severity; and (3) to identify potential risk factors for competition injury.
METHODS
Study design
Prospective cohort study.
Study population
Boxing, judo, taekwondo, and wrestling athletes competing at the Beijing 2008, London
2012, and Rio de Janeiro 2016 Olympic Games.
Data sources
Injury data were obtained from the IOC injury and illness surveillance system for multisport
events from the Beijing 2008, London 2012, and Rio de Janeiro 2016 Olympic Games. The
methodology for the IOC injury and illness surveillance system has been outlined
previously.[11-14] In brief, all National Olympic Committee (NOC) medical teams were
invited to report the daily occurrence (or non-occurrence) of injuries and illnesses using an
electronic report form. Concurrently, information on all athletes treated for injuries in the
polyclinic and all other medical venues operated by the medical staff of the Local Organizing
Committee (LOC) at each Olympic Games were collected through an electronic medical
record system. The following injury data were collected: accreditation number, name, sport
and event, whether the injury occurred in competition or training, date and time, injured body
part, type of injury, cause of injury, and estimated time lost from competition or training.
Exposure data were obtained from the official tournament records (i.e., draw sheets) that
were compiled for each combat sport tournament at each Olympic Games. These draw sheets
typically contain information about all individual contests, including name and nationality of
competing athletes, weight division, tournament round, and outcome and duration of contest.
The information on the draw sheets was cross-validated with information available from
https://www.sports-reference.com/, a website that aggregates various sports statistics, and
information available on the websites of the international sports governing body for each
Olympic combat sport (i.e., the International Boxing Association, https://www.aiba.org/;
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International Judo Federation, https://www.ijf.org/; World Taekwondo,
http://www.worldtaekwondo.org/; and United World Wrestling,
https://unitedworldwrestling.org/).
Operational injury definitions
Injury was defined as a new or recurring musculoskeletal complaint, concussion, or other
medical condition incurred in competition during the Olympic Games receiving medical
attention, regardless of the consequences with respect to absence from competition or
training.[11-14] That is, re-injury after full recovery was recorded, whereas exacerbation of
pre-existing injury before full recovery was not recorded. In cases where a single incident
caused multiple injury types, only the most severe diagnosis was recorded. Estimated number
of days absent from training or competition was used to determine injury severity. Injury
severity was categorised using the following time bins: 0 days, 1-7 days, 8-28 days, >28 days,
as recommended by the IOC consensus statement on methods for recording and reporting of
epidemiological data on injury and illness in sport.[15] In regard to diagnoses, all recorded
injuries were coded and categorised by body region and area as recommended by the IOC
consensus statement on methods for recording and reporting of epidemiological data on
injury and illness in sport.[15]
Data management and statistical analysis
For each combat sport, male and female weight divisions were dichotomised into ‘light’ and
‘heavy’ weight categories. If there was an even number of weight divisions, then the lighter
and heavier halves of the weight divisions were designated as ‘light’ and ‘heavy’,
respectively. If there was an odd number of weight divisions, then the lightest weight division
was designated as ‘light’ and the lighter and heavier halves of the remaining weight divisions
were designated as ‘light’ and ‘heavy’, respectively. See Supplementary Table 1 for a
detailed overview of the dichotomised weight divisions for each combat sport, sex, and event.
Individual contests were dichotomised as ‘preliminary’ and ‘final’ tournament rounds. That
is, preliminary tournament rounds comprised contests prior to quarterfinals (e.g., qualification
rounds, rounds of 64, rounds of 32, and rounds of 16); while final tournament rounds
comprised all subsequent contests (e.g., quarterfinals, semifinals, finals, and if applicable,
repechage rounds and bronzefinals). Competition rules are revised from time to time, albeit
major changes are relatively infrequent. The two most noteworthy rule changes that occurred
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during the study period were the overhauling the scoring system in taekwondo after Beijing
2008 and the removal of protective headguards in men’s boxing after London 2012. Thus,
individual contests in taekwondo and men’s boxing were dichotomized into pre- and post-
major rule change accordingly.
Injury incidence rates per 100 registered athletes (IIRRA), per 1,000 athlete-exposures (IIRAE),
and per 1,000 minutes of exposure (IIRME) were calculated with 95% confidence intervals
(CI) using standard formulae for Poisson rates.[16] Combat sports and subgroups (e.g.,
female versus male, heavy weight divisions versus light weight divisions, final tournament
rounds versus preliminary tournament rounds, losers versus winner, and post- versus pre-
major rule changes) were univariately compared by computing the injury incidence rate ratio
(RR), whereby two injury incidence rates were deemed statistically different from one
another if the 95%CI for the RR did not include the null value (i.e., 1). All statistical analyses
were conducted using the statistical software R, version 3.5.1 (R Foundation for Statistical
Computing, Vienna, Austria).
Ethical considerations
This research was approved by the Macquarie University Human Research Committee
(reference number: 5201700320) and was conducted in accordance with the requirements of
the National Health and Medical Research Council’s National Statement on Ethical Conduct
in Human Research (2007; updated May 2015).
RESULTS
Combat sport event at Beijing 2008, London 2012, and Rio de Janeiro 2016 Olympic Games
comprised a total of 3,412 athlete registrations, 7,712 athlete exposures, and 40,250 minutes
(670.8 hours) of exposure. Many athletes were registered at more than one event; hence, the
number of unique athletes was 2,805. Of these, 750 (26.7%) were boxing athletes, 925
(33.0%) were judo athletes, 316 (11.3%) were taekwondo athletes, and 814 (29.0%) were
wrestling athletes. They comprised 777 (27.3%) female and 2,028 (72.3%) male athletes.
Injury incidence
A total of 315 competition injuries were recorded among combat sport athletes during the
three Olympic Games. The overall IIRAR, IIRAE, and IIRME were 9.2 (95%CI 8.2, 10.3), 40.9
(95%CI 36.5, 45.6), and 7.8 (95%CI 7.0, 8.7), respectively (Table 1). The highest IIRME were
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observed in judo (9.6 [95%CI 7.8, 11.7]) and boxing (9.2 [95%CI 7.6, 10.9]), followed by
taekwondo (7.7 [95%CI 5.6, 10.5]) and wrestling (4.8 [95%CI 3.6, 6.2]). Compared to
wrestling, the IIRME was significantly higher in boxing (RRME 1.91 [95%CI 1.31, 2.62]), judo
(RRME 2.00 [95%CI 1.44, 2.79]), and taekwondo (RRME 1.61 [95%CI 1.08, 2.41]). There was
no significant difference in IIRME between judo and boxing (RRME 1.05 [95%CI 0.80, 1.37]).
Although the IIRME in taekwondo was 19% and 16% lower than in judo (RRME 0.81 [95%CI
0.51, 1.16]) and boxing (RRME 0.84 [95%CI 0.60, 1.20]), respectively, the IIRME were not
significantly different.
[insert Table 1 near here]
Injury severity
Of the 315 recorded injuries, 309 (98.1%) provided estimates of the number of days absent
from training or competition. Of these, 155 (50.2%) were 0 days absence, 61 (19.7%) were 1-
7 days absence, 53 (17.2%) were 8-28 days absence, and 40 (12.9%) were >28 days absence.
The proportion of injuries resulting in >7 days absence was highest in wrestling (39.6%) and
judo (35.9%), followed by taekwondo (32.5%), and lowest in boxing (21.0%) (Figure 1).
[insert Figure 1 near here]
Injury profile
Overall, the most commonly injured body region was the head and neck (35.9%), followed
by the upper limb (31.1%) and lower limb (26.3%). There were distinct differences in the
distribution of injury by body location across the combat sports (Table 2). The highest and
lowest proportions of head and neck injuries were observed in boxing (62.1%) and
taekwondo (4.8%), respectively. Upper limb injuries were particularly frequent in judo
(42.6%), while the lower limb was the most commonly injured body region in taekwondo
(59.5%) and wrestling (45.5%). Overall, the most commonly injured tissue types were
superficial tissue and skin (42.9%) and ligament and joint capsule (31.4%), with the most
frequent types of pathology being joint sprain (31.4%), laceration and abrasion (23.2%), and
contusions (19.7%). Concussion accounted for 3.2% of all recorded injuries. There were
similarities and differences in the distribution of injury by type of pathology across the
combat sports (Table 3). Contusion was common in all combat sports (i.e., boxing: 18.5%;
judo: 16.0%; taekwondo: 28.6%; and wrestling: 21.8%). Laceration was particularly common
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in boxing (41.1%), while joint sprain was predominant in judo (47.9%), taekwondo (33.3%),
and wrestling (40.0%).
[insert Table 2 near here]
[insert Table 3 near here]
Risk factors for injury
Overall, there was no significant difference in IIRME between females versus males (RRME
1.06; 95%CI 0.82, 1.36), heavy versus light weight categories (RRME 0.97 [95%CI 0.76,
1.24]), or final versus preliminary tournament rounds (RRME 1.00 [95%CI 0.78, 1.27]). There
were some notable differences in potential risk factors across the combat sports (Figure 3).
Compared to their male counterparts, female taekwondo athletes had lower IIRME (RRME 0.69
[95%CI 0.57, 1.95]), whereas female judo athletes had higher IIRME (RRME 1.30 [95%CI
0.90, 2.03]); however, the differences were not statistically significant in either of the sports.
Compared to their light weight counterparts, heavy weight judo athletes had significantly
lower IIRME (RRME 0.57 [95%CI 0.33, 0.97]), whereas heavy weight boxing athletes had
higher IIRME (RRME 1.32 [95%CI 0.93, 1.88]), albeit the difference was not significant in
boxing. There was no significant change in IIRME in taekwondo following major rule changes
(i.e., electronic scoring and more points awarded for head kicks) that were introduced after
the Beijing 2008 Olympic Games (RRME 0.81 [95%CI 0.44, 1.50]). There was a three-fold
increase in IIRME for male boxers after rule changes (i.e., removal of protective headguard)
that were introduced after the London 2012 Olympic Games (RRME 3.00 [95%CI 2.07,
4.36]).
[insert Figure 3 near here]
Injury and performance
Overall, athletes losing a contest had significantly higher IIRME than their winning opponents
(RRME 3.59 [95%CI 2.68, 4.79]). The magnitude of this effect was largest in wrestling (RRME
6.40 [95%CI 2.57, 15.91]) and smallest judo (RRME 2.67 [95%CI 1.56, 4.55]) (Figure 4).
[insert Figure 4 near here]
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DISCUSSION
This study highlights important differences in the burden of injury in Olympic combat sports.
On average, these athletes sustain one injury every 2.1 hours of competition, with
significantly greater risk of injury in boxing, judo, and taekwondo than in wrestling. About
70% of injuries are minor, with higher proportions moderate to severe injuries in wrestling,
judo, and taekwondo than in boxing.
Injury incidence
We found that Olympic combat sport athletes sustained 40.9 competition injuries per 1,000
exposures or 7.8 injuries per 1,000 minutes of exposure (469.6 injuries per 1,000 hours of
exposure), which equate to 1 injury every 24 exposures or 2.1 hours of exposure,
respectively. The risk of injury varied significantly between combat sports, but the relative
risk of injury depended on the choice of denominator. The observed IIRAE, in descending
order, were 76.6 in boxing, 46.4 in taekwondo, 34.0 in judo, and 22.7 in wrestling, which
suggests that the risk of injury in boxing was about 1.7 times higher than in taekwondo, 2.3
times higher than in judo, and 3.3 times higher than in wrestling. However, the duration of
contests is not the same for all Olympic combat sports. When factoring the actual time at-
risk, the observed IIRME, in descending order, were 9.6 in judo, 9.2 in boxing, 7.7 in
taekwondo, and 4.8 in wrestling. This suggests that the risk of injury is similar in judo and
boxing, which is 1.2 times higher than in taekwondo and about 2 times higher than in
wrestling. The differences in relative risk outlined above underscores the importance of using
injury incidence rates accounting for actual time at-risk when comparing injury risk across
combat sports.
Relatively few studies have reported on injury risk in Olympic combat sports using exposure
units that account for time at-risk, with IIRME estimates ranging from 13.8 to 20.4 in
boxing,[17-19] 16.3 in taekwondo,[20] 10.9 in judo,[21], and 5.9.[22] The IIRME estimates in
our study appear to be lower than in these previous studies. Although the reasons for the
inconsistencies in IIRME estimates is unclear, it is likely to be related to variability in
methodology (e.g., injury surveillance methods and operational injury definitions), study
populations (e.g., level of competition, age groups, and sex), and context (e.g., competition
rule changes over time).
Injury severity
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The distribution of injuries by severity varied across combat sports, with the proportion of
injuries resulting in >7 days absence from participation being higher in wrestling (39.6%) and
judo (35.9%), followed by taekwondo (32.5%), and lowest in boxing (21.0%).
Notwithstanding the limited number of previous studies reporting on the distribution of
injuries by severity, the available data appear to conform with our findings. That is, while no
studies have reported on the distribution of injury severity in terms of time loss in boxing or
judo, one study reported that 32% of injuries in taekwondo resulted in >7 days absence from
participation and one study found that 34% of injuries in wrestling required >10 days absence
from participation.[20,24] It is important to note that the present study relied on estimates of
time lost from participation. The higher proportion of moderate and severe injuries in judo
and wrestling is likely related to the fact that knee ligament injuries feature prominently in
these grappling style combat sports, in which athletes are frequently exposed to direct or
indirect contact through various takedown techniques (i.e., techniques aiming to bring the
opponent to the ground).[9,10,23] This suggests that injury prevention strategies specifically
targeting these types injuries may be particularly important to reduce the burden of injury in
judo and wrestling.
Injury profile
We have identified distinct differences in injury profiles across combat sports, which are
generally consistent with those reported in previous reviews.[7-10] Differences in injury
profiles across combat sports have been attributed to unique features of the sports such as
competition rules (e.g., permissible techniques and targets, mandatory protective
equipment).[25,26] For instance, although strikes to the head and trunk are permissible in
both boxing and taekwondo, only the latter permit the use of kicks. This increases the typical
distance between opponents and reduces the frequency of punching, which in turn results in
fewer head impacts and more distal lower limb injuries in taekwondo compared to boxing.
Another example is that, unlike the striking styles (i.e., boxing and taekwondo), the grappling
styles (i.e., judo and wrestling) allow direct and indirect contact to the lower limbs through
various techniques aiming to bring or pin the opponent to the ground, which explains why
knee ligament injuries feature prominently in the grappling styles.[9,10,23]
Risk factors for injury
Competition rules are revised from time to time, albeit major changes are relatively
infrequent. Although such rule changes are not necessarily introduced to improve athlete
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safety, they are nonetheless factors that may alter the risk of injury. For instance, the post-
Beijing 2008 rule changes in taekwondo were introduced to improve transparency of the
scoring system and make the sport more entertaining for audiences. To encourage taekwondo
athletes deploying more head kicks, the rule changes involved increasing the number of
points awarded for head kicks and decreasing the minimum impact required to score points
from head kicks. Contrary to initial concerns about the potential for increasing the risk of
injury, our data showed a slight decrease in injury rates after the rule change. A possible
explanation for this observation is that although the frequency of head kicks has increased, a
greater emphasis on speed has resulted in a general decrease in the impact forces imparted
during the delivery of head kicks. Unlike the rule change in taekwondo, the decision to
eliminate protective headguards in men’s boxing was based on safety concerns. That is, a
cross-sectional study conducted by the amateur boxing governing body claimed that match
stoppages due to repeated head blows were less common when headguards were not
worn.[27] The rule change has been controversial, partly because although the rate of match
stoppages due to repeated head blows decreased by 43%, the rate of lacerations increased
430%; and partly because of the paradox created by eliminating headguards in men’s, but not
women’s, boxing without any clear rationale for the disparate practice. Our data showed a
three-fold increase in overall injury risk for male boxers after the elimination of protective
headguards. This suggests that carefully designed research is needed to elucidate the
relationship between injury risk and protective headguards in both women’s and men’s
amateur boxing.
Injury and performance
Unsurprisingly, the outcome of contests was strongly associated with occurrence of injury,
with losing athletes having a 3.6 times higher injury incidence rate compared to their winning
opponents. Although the direction of this relationship cannot be established in this study, it
seems more plausible that sustaining an injury results in poor performance rather than poor
performance increasing the risk of injury. If so, then it follows that avoiding injury is key to
improved performance and athletic success. This view concurs with studies concluding that
injuries have a detrimental impact athletic success and that injury prevention should therefore
be a priority for maximising athletic performance.[28,29]
Strengths and limitations
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This is the first study to compare the epidemiology of competition injuries in Olympic
combat sports using directly comparable injury and exposure data. Injury data were obtained
from a high-quality, multisport injury surveillance system, which ensured consist and
standardised recording of injuries for all combat sports. Furthermore, actual time exposed to
risk of injury was obtained from official tournament records, which facilitated comparison of
injury incidence rates per unit time exposed. Notwithstanding these strengths, this research
has some limitations. Firstly, injuries are likely to be underreported, thereby underestimating
the true risk of injury in Olympic combat sports. Although the rate of returned daily injury
report forms was very high at the three Olympic Games,[12-14] there is good reason to
believe that not all injuries were reported, in particular less severe injuries. That is, injured
athletes do not always seek medical attention, especially for injuries without time loss,[30-32]
and all NOC medical teams may not have been fully aware of the broad injury definition
applied in the IOC injury surveillance system.[13] However, we have no reason to believe
reporting varied by type of combat sport, which means our measures of relative risk are
unlikely to be impacted by underreporting. Secondly, although NOC and LOC medical teams
are comprised of highly experienced sports medicine practitioners, the accuracy and internal
validity of their reported data is not known. Thirdly, injury severity was based on estimates of
time loss provided at the time the athletes sought medical attention, the accuracy of the
estimated time loss is unknown. Fourthly, although we were unable to map all recorded
injuries to a specific exposure, injuries could always be attributed to a particular combat
sport. This may have decreased the statistical power in our rate ratio calculations for various
risk factors (i.e., sex, tournament round, and contest outcome), but it has not impacted our
estimates of relative risk of injury between combat sports. Lastly, this study included
competition data from three Olympic Games, which may limit the generalisability of the
findings. It is possible that the injury risk and profile is different in the training-setting and
among combat sport athletes competing at non-Olympic tournaments (i.e., at the local,
regional, national levels) due to potential differences in level of fitness, training load,
technical abilities, and competition experience. It is also possible that the injury risk and
profile is different at other top-level competitions (i.e., World Championships) due to
differences in tournament schedules (e.g., number of weight divisions and average number of
exposures per athlete). Our findings should be interpreted in the light of these limitations.
Recommendations and implications
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Future studies of injuries in combat sports are strongly recommended to adhere to definitions
and data collection procedures outlined in the recent IOC consensus statement on methods for
recording and reporting epidemiological data from injury and illness surveillance in
sports.[15] Injury incidence rates should be reported using both per athlete exposure and
actual time at-risk (e.g., minutes of exposure) to facilitate comparisons within and across
combat sports. Injury severity should be measured and reported using the actual number of
days absent from competition and training. Classification of injury diagnoses (i.e., by
anatomical location and type of injury) should adhere to standardised sports-specific coding
systems such as the revised versions of the Sport Medicine Diagnostic Coding System
(SMDCS) or the Orchard Sports Injury and Illness Classification System (OSIICS).[15,33]
We hope that our findings will facilitate the development and implementation of evidence-
informed injury prevention efforts and drive policy change in Olympic combat sports,
thereby making these sports safer and more enjoyable for athletes. Our findings show that
major rule changes can significantly impact the risk of injury, which suggests that combat
sport governing bodies could deliberately improve the safety of their sports by implementing
new competition rules designed to reduce injury risk. However, combat sport governing
bodies need to mindful of the potential for unintended consequences when implementing new
competition rules and are therefore strongly encouraged to partner with sports injury
prevention and implementation scientists when planning to introduce major rule changes.
Major rule changes notwithstanding, there is a need for investigating a broader range of risk
factors and injury mechanisms in combat sports, especially potentially modifiable factors that
may be targeted by injury prevention interventions. For instance, although the relationship
between training load and injury is well established in the sports injury literature,[34] it
remains largely unexplored in context of combat sports. Another important factor to be
considered is the rapid weight loss practices that are prevalent in the combat sports.[35]
Previous studies have documented a range of potential negative health implications
associated with rapid weight loss practices, including severe dehydration resulting in acute
cardiovascular problems (e.g., ischaemic heart disease and stroke) and increased
susceptibility to traumatic brain injury.[36,37] There are even documented cases of deaths
linked to rapid weight loss practices in combat sports.[38] Further research to elucidate the
relationship between rapid weight loss practices and injury risk in combat sports is warranted.
For international competitions such as the Olympic Games, it would also be useful to
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consider the potential impact of long-distance air travel (e.g., recovery, sleep disruption, and
acclimation) on injury risk. Although the association between of travel and injury risk has
been investigated in other sports,[39,40] it remains unexplored in context of combat sports.
Finally, it is especially important to consider and account for the multifactorial, dynamic, and
complex nature of sports injury causation. Future studies are therefore strongly encouraged to
adopt frameworks that incorporates this inherent complexity.[41-44]
CONCLUSION
Olympic combat sport athletes sustained, on average, 1 injury every 2.1 hours of competition.
The risk of injury was significantly higher in boxing, judo, and taekwondo than in wrestling.
About 30% of injuries sustained during competition resulted in >7 days absence from
participation, with higher proportions in wrestling, judo, and taekwondo than in boxing.
Overall, there was no significant difference in injury risk by sex, weight category, or
tournament round, but defeated athletes were more than three times more likely to sustain an
injury compared to their winning opponents. There is a need for identifying modifiable risk
factors for injury in Olympic combat sports, which in turn can be targeted by injury
prevention initiatives to reduce the burden of injury among combat sport athletes.
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ACKNOWLEDGEMENTS
We would like to thank the Medical & Scientific Department of the International Olympic
Committee for providing access to injury surveillance data from the Beijing 2008, London
2012, and Rio de Janeiro 2016 Olympic Games. We would like to acknowledge the
cooperation and contribution of all the medical staff of the Local Organizing Committees and
National Olympic Committees who volunteered their time to collect and report injury data
during the Beijing 2008, London 2012, and Rio de Janeiro 2016 Olympic Games.
FOOTNOTES
Twitter @RLystad, @TSoligard, @larsengebretsen
Contributors RPL, TS and LE conceived the study. TS and LE provided the injury data.
RPL, AA, and IR collated the exposure data. RPL conducted the analysis and wrote the first
draft of the manuscript. RPL, TS, and LE interpreted the findings and reviewed and edited the
manuscript. All authors approved the final manuscript.
Funding The International Olympic Committee funded the collection of the Olympic Games
injury data.
Competing interests RPL, AA, and IR declare that they have no potential conflicts of
interest that are directly relevant to this study. TS and LE work in the Medical and Scientific
Department of the IOC as Scientific Manager and Head of Scientific Activities, respectively.
Patient consent Not required.
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FIGURE LEGENDS
Figure 1. Distribution of injuries by severity category for each combat sport.
Figure 2. Risk matrix plot of injury burden for each combat sport.
Figure 3. Forest plots of injury incidence rate ratios per 1,000 minutes of exposure for each
combat sport by sex (A), weight category (B), tournament round (C), and pre/post-major rule
changes (D).
Figure 4. Forest plot of injury incidence rate ratios per 1,000 minutes of exposure for each
combat sport by contest outcome.
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Table 1. Overview of injury and exposure data and injury incidence rates for each combat
sport.
Boxing Judo Taekwondo Wrestling
Injuries, n 124 94 42 55
Athlete registrations, n 857 1,163 384 1,008
Athlete exposures, n 1,618 2,762 906 2,426
Minutes of exposure, n 13,536 9,807 5,430 11,476
Injury incidence rate per 100
athlete registrations (95%CI)
14.5
(12.0, 17.3)
8.1
(6.5, 9.9)
10.9
(7.9, 14.8)
5.5
(4.1, 7.1)
Injury incidence rate per 1,000
athlete exposures (95%CI)
76.6
(63.7, 91.4)
34.0
(27.5, 41.7)
46.4
(33.4, 62.7)
22.7
(17.1, 29.5)
Injury incidence rate per 1,000
minutes of exposure (95%CI)
9.2
(7.6, 10.9)
9.6
(7.8, 11.7)
7.7
(5.6, 10.5)
4.8
(3.6, 6.2)
OLYMPIC COMBAT SPORT INJURIES
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Table 2. Frequency (%) of injuries by body region and area for each combat sport.
Region/Area Boxing
(n=124)
Judo
(n=94)
Taekwondo
(n42)
Wrestling
(n=55)
Head and neck 77 (62.1) 24 (25.5) 2 (4.8) 10 (18.2)
Head 75 (60.5) 22 (23.4) 2 (4.8) 10 (18.2)
Neck 2 (1.6) 2 (2.1) - -
Trunk 10 (8.1) 3 (3.2) 2 (4.8) 6 (10.9)
Chest 2 (1.6) 2 (2.1) - 4 (7.3)
Abdomen 1 (0.8) - - -
Thoracic spine 4 (3.2) 1 (1.1) - 1 (1.8)
Lumbosacral 3 (2.4) - 2 (4.8) 1 (1.8)
Upper limb 31 (25.0) 40 (42.6) 13 (31.0) 14 (25.5)
Shoulder 6 (4.8) 11 (11.7) 2 (4.8) 7 (12.7)
Upper arm 2 (1.6) 1 (1.1) - -
Elbow 8 (6.5) 18 (19.1) - 3 (5.5.)
Forearm 6 (4.8) - - -
Wrist 6 (4.8) 8 (8.5) 8 (19.0) -
Hand 3 (2.4) 2 (2.1) 3 (7.1) 4 (7.3)
Lower limb 6 (4.8) 27 (28.7) 25 (59.5) 25 (45.5)
Hip/groin - 1 (1.1) - -
Thigh - 4 (4.3) 7 (16.7) 4 (7.3)
Knee 2 (1.6) 16 (17.0) 7 (16.7) 20 (36.4)
Lower leg - - 1 (2.4) 1 (1.8)
Ankle 4 (3.2) 3 (3.2) 5 (11.9) -
Foot - 3 (3.2) 5 (9.5) -
OLYMPIC COMBAT SPORT INJURIES
24
Table 3. Frequency (%) of injuries by tissue and pathology type for each combat sport.
Tissue/Pathology type Boxing
(n=124)
Judo
(n=94)
Taekwondo
(n42)
Wrestling
(n=55)
Muscle / Tendon 9 (7.3) 8 (8.5) 5 (11.9) 12 (21.8)
Muscle injury 7 (5.6) 5 (5.3) 4 (9.5) 5 (9.1)
Tendinopathy 2 (1.6) 1 (1.1) 1 (2.4) 6 (10.9)
Tendon rupture - 2 (2.1) - 1 (1.8)
Nervous 8 (6.5) 1 (1.1) 2 (4.8) -
Brain and/or spinal cord injury 8 (6.5) 1 (1.1) 1 (2.4) -
Peripheral nerve injury - - 1 (2.4) -
Bone 6 (4.8) 2 (2.1) 6 (14.3) 2 (3.6)
Fracture 5 (4.0) 2 (2.1) 6 (14.3) 2 (3.6)
Bone stress injury 1 (0.8) - - -
Cartilage / Synovium / Bursa 3 (2.4) 4 (4.3) - 2 (3.6)
Cartilage 1 (0.8) 3 (3.2) - 1 (1.8)
Arthritis / Synovitis / Bursitis 2 (1.6) 1 (1.1) - 1 (1.8)
Ligament / Joint capsule 18 (14.5) 45 (47.9) 14 (33.3) 22 (40.0)
Joint sprain 18 (14.5) 45 (47.9) 14 (33.3) 22 (40.0)
Superficial tissues / Skin 74 (59.7) 32 (34.0) 13 (31.0) 16 (29.1)
Contusion (superficial) 23 (18.5) 15 (16.0) 12 (28.6) 12 (21.8)
Laceration / Abrasion 51 (41.1) 17 (18.1) 1 (2.4) 4 (7.3)
Other / Unknown / Unspecified 6 (4.8) 2 (2.1) 2 (4.8) 1 (1.8)